PATENT LITERATURE 1 describes a pluggable optical transceiver to be used in a 10G-EPON station-side apparatus. This optical transceiver is provided with an optical sub-assembly implemented by a single-core bidirectional 3-port Bi-D (Bi-Directional optical module).
The optical sub-assembly includes a TOSA (Transmitter Optical sub-Assembly) for 10G, a TOSA for 1G, and a ROSA (Receiver Optical sub-Assembly) that corresponds to both 10G/1G.
The TOSA for 1G is included in the 10G-EPON optical transceiver so that, when 10G-EPON is introduced by installing a 10G-EPON station-side apparatus in place of an EPON station-side apparatus, service is also continuously provided to existing home-side apparatuses that have downlink transmission rate of 1G.